The present invention relates in essence to a method for electric ignition of any oxy-fuel burner and to the burners themselves.
The electric ignition of air-fuel burners, consisting in using an H.T. discharge into the gaseous flow emerging from these burners, has not been applied to oxy-fuel burners until now. As a matter of fact, the temperature and oxidation level within an oxy-fuel flame are such that the electrodes utilised for this discharge are destroyed rapidly by melting and/or gas cutting. The ignition of oxy-fuel burners was consequently impossible without ancillary apparatus such as pilot burners or glow-type igniters, or else the application of the arc of an arc furnace for example, in some special cases.
It is known that oxy-fuel burners are supplied separately with oxygen and a gaseous fuel and that the jets issuing from the same are mixed at a particular distance from their front surface, in a proportion close to stoichiometric, these jets causing recirculation flows between them and in the space situated between the said area and the said front surface, which carry a fraction of the burnt gases towards the burner. A gaseous mixture denuded partially of oxygen and fuel, and the composition of which, being the relative proportion of oxygen and fuel, varies locally as a function of the geometry of the burner, that is to say of the position and distribution of the orifices from which the jets had emerged, is thus obtained between the two jets issuing from the burner.